Electric signal



Nov. 1, 1927. 1,647,858

(3. w. DUNHAM ELECTRIC SIGNAL Filed Dec. 7. 1923 INVENTOR.

' poles2 and 2', connected by a Patented Nov. 1, 1927.

v UNITED STATES} 1,647,858 PATENT OFFICE.

CHARLES W. DUN HAM, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH &SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

ELECTRIC SIGNAL.

Application filed December 7, 1923. Serial No. 679,057.

My invention relates to electric signals, and particularly tosignals of the type comprising a signal arm arranged-to oscillate. Signals embodying my invention are particularly adapted for, though in no way limited to, use as highway crossing signals.

I will describetwo forms of signalsembodyingmy invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a view, partly diagrammatic, showing in front elevation, one form of signal embodying my invention. Fig. 2 ;is a View showing a modification of the signal illustrated in F ig. 1. Figs. 3 and .4 are detail views showing parts of the signal shown in Fig. 2. Fig. 5 is a detail view showing, in side elevation, the magnet Ashown in Fig. 1., Fig. 6 is a view showing another modification of the signal illustrated in Fig. ,1 and also embodying my invention. y v. I

Similar reference characters-refer to similar parts in each-of the several views.

Referring first to Fig. ,1, the signal comprises a; signal arm pivotally supported on a shaft/i. .This. arm carries at its lower end atarget 3 which may be providedwith some suitable warning-legend, as the word StopFt Supported also on shaft 4. is a yoke Cof magnetizable material comprising two downwardly projecting diverging legs 6 and-7. These legs are separately and independently pivotally mounted on the shaft. 4. Legs 6 and 7 areprovided with outstanding lugs 69 and-7 respectively, arranged.

to engage ,arm B,-and the parts are so disposed that they arezbiased by gravity into the positionin whichthey areshown in the drawing, Under these conditions arm B assumesa central position and the parts are in equilibrium. i i @Anelectromagnet A, having two spaced ack strap .20

and-each pole provided with a winding 1 as shown in Fig. 5, is so dis osed that the poles 2 and 2 extend npwar ly betweenthe legs 6..and 7 of yoke C. Each leg 6 and 7 preferably bridges the poles 2 and 2*" of magnetA. I ArmB operates a circuitcontroller J as follows:. i I

,The upper end-of arm B extends beyond the pivot 4' to form a projection 5 which enters a recess 8 in a plate 8. This plate is supportedjby means of twowpins 9 and "9 which project into slots 10 and 10 respectively lll'the plate 8. The upper edge of plate 8 is provided with a conducting strip 11 arranged to co-operate with two fixed contact members 12 and 13 so that when arm B is in its central positi0i1, contact'l2 should be noted that there is considerable clearance between projection 5 and the edges of recess 8 and therefore there is consider able lost motion between arm B and plate 8. Magnet A is supplied with current from some suitable source of energy such as a battery 25 over contact 12ll 13 and a circuit controller 14 controlled in any suit able manner. When this circuit controller l i s open the parts assume the positions shown 1n the drawing in which the poles of magnet A are approximately midway between the legs 6 and 7 of yoke G. If, now, circuit controller 14 is closed, magnet A creates a magnetic field which tendsto' draw both legs 6and 7 toward the poles 2; It is practically impossible, however, to center the magnet so.

accurately that'the forces acting on both legs are exactly equal but one leg will the' magnet more strongly than leg 7, the lug 6 on this leg will engage arm B and approaches the magnet the pull exerted on this log is increased and at the same time leg 7 is moved away from the magnet and the pull on this latter leg isdecreased. Arm, B-is therefore swung toward the righttill projection!) moves plate 8 to the left to always be drawn more strongly than the V other. Assuming that leg 6 is drawn toward swing the arm to the right; As the leg 6 break the circuit. forQmagnet-"A at contact 7 11,13.- Under the influence of gravity, the

arm B then swings back to its central position thus again closing the circuit for magnet A. Due, however, to theinertia of the moving parts, arm B swings past the centralp'ositionand, leg 7 then being closerto the magnet poles than leg 6, the arm B is drawn to the left by the .magnet until the circuit for the magnet is again broken, this time at conta-ct 1211. It-will be. clear therefore In case the amplitude of vibration of arm B builds up to such value that the inertia of the arm swings one of the legs, as leg 6, against the poles of the magnet the arm can continue tomove in the same direction and simply move away from the lug 6 engaging this lug on its return swing to move the leg 6 away from the poles again. If circuit controller 1a is opened, thesignal returns, under the influence of gravity, to the position shown in the drawin In the modification shown in Fig. 2 the arm- Bis pivoted as before'on shaft 4 and is provided at its upper end with a yoke (3 having two upwardly projecting integral.

legs 6-and 7. The magnet A is located above these legs with downwardly projecting poles approximately midway between legs 6 and 7 when the'arm is at rest as shown in the drawing.

The circuit controllerJ comprises a shaft 15 which is operatively connected with the arm B so that when the arm oscillates the shaft also oscillates back and forth through a small angle. Rigidl-y fastened to shaft 15 is a dog 16 compr'sing as best shown in Figs;

3 and 4, a flat-plate 16" outstanding from the shaft and having at its outer extremity a projection 17 extending from the face of the dog and parallel with shaft 15. This dog 16 operates a'dislr 18 loosely mounted on shaft-15 and rotatable thereabout. 1 The edge of this disk is provided with a notch 19 capable of receiving the'projection 17 on dog l6 with considerable clearance. A contactmember 11 mounted on the periphery of disk 18 co-operates with two fixed contact members 12 and :13 to control the electromagnet A in the same manner as explained for the control of magnet A by circuit controller J in Fig. 1. The operation of the signal will be understood from the description of the operation of the signal'shownin Fig. 1.

In the modification shown in-Fig. 6, the pivoted arm B is provided with an armature C comprising a single 'upstandingleg. The magnet A is located above this armature and comprises-a back strap 20 and threespaced,

downwardly projecting poles 2, 2, and 2". A winding 20 is located on leg 2?; The energization of this winding is controlled by, a circuit controller similar to the circuit controller J of Fig.2 and omitted from Fig; 6 for the sake of simplicity; The parts areso proportioned that when the signal is deenergized, arm '13 is biased to a position in which-armature C is adjacent pole face 50" of pole 2. When the signal is'energized armature C is positively drawntoward pole face 50 of pole 2 and pole face 50 of pole 2 alternately. i

Signals embodying my invention'are particularly adapted for, though in noway limited to, use as-three aspect signals, that is' signals in which the signal arm is arranged to be latched up in an inclined position when the signal operating mechanism is de-energized.

Although I have herein shown and-described only three forms of electric signals embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit'and scope ofmy invention.

'laving thus described my invention, what I claim is:

'1.-In combination, a pivoted arm biased to 'a central position, a magnetizable yoke operatively connected with said arm and having two spaced legs, an electromagnet intermediate said legs and so disposed that when said magnet is energized one such leg is drawn toward the magnetto swing the arm away from'its centralposition, anda circuit for said magnet closed only when said arm-is nearsuch central position.

2.1n combination, a pivoted arm biased to" a'oentral position, a yoke of magnetizablef material attachedto said armand having two upwardly projectinglegs, anelectromagnet having a pole located above said yoke intermediate said legs for swinging said arm altcrnately'in opposite directions away from said cent-ralposition, a shaft fixed to said armand rotatable thereby, a dog rigidly fastened to said shaft and having an outstandingfinger, a disk freely rotatable on said shaft and provided with a recess for receiving said finger with considerable clearance, and a circuit controller operated by said disk for controlling said electromagnet. l. In combination, a pivoted arm biased tdacentnlposition,a single ,magnet for positively swinging said arm away from said cent al positionalternately in opposite directions, and "means for energizing said mag: net only when said arm is near its central position.

' In combination, a pivoted arm biased to a central position, a single magnet "for positively swinging said arm alternately to extreme positions on opposite sides of said centrala ijosition, and means" for at times supplying energy to said magnet but for interru'ptin-g such supply "when saidarm approaches either such extreme position.

6 ;-*In combination, a pivoted arm: biased to a'central position, a normally closed cir position in which said magnet is between said legs but is slightly closer to one such leg than to the other so that one said leg approaches the magnet 'when the magnet is energized, and a normally closed circuit con troller for controlling saidmagnet and arranged to be opened when said arm is moved away from said central position whereby said legs are alternately swung toward said magnet to oscillate said arm.v

In testimony whereof I afiix mysignature.

CHARLES W DUNHAM; 

